Shallow depth of field with APS-C camera

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Brentor

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I have a mixture of Canon DSLRs, none of which are that new, some APS-C, others full frame . Most of my photography is landscape and birds. I also take photos of flowers/plants and occasionally people, more so now since having two grandchildren. My fastest lenses are f1.8 and I really like the way they throw the background out of focus when used wide open on full frame cameras.

I recently bought a R7 which is great for birds. However if I want to travel light and just take the R7 and a few lenses, how to I get similar shallow depth of field as I do with the FF cameras, should the need arise? I do not want to spend a small fortune on really fast lenses, so is the best option controlling the distances between the camera, the subject and the background? Or is it just not possible?
 
DoF is a function of focal length and aperture, the reason smaller sensors seem to give more DoF is because the equivalent lenses are shorter focal length, so you can get shallower depth of field by using a longer lens.
 
sirch said:
DoF is a function of focal length and aperture, the reason smaller sensors seem to give more DoF is because the equivalent lenses are shorter focal length, so you can get shallower depth of field by using a longer lens.
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Which then puts you further away from the subject which also has the function of changing the perspective.

So to answer the OP succinctly; the effective difference in Aperture is approximately 1 stop, which isn’t a great deal in the grand scheme of things.

The 85mm 1.8 on crop would have slightly more DoF than a 135 f2, but not quite as much as a 135 2.8.

In other words, from a purist perspective an 85 1.4 is akin to the 135 f2, but it’s not such a big deal.

The OP’s problems would really start if they had been used to f1.4 lenses, as going wider would be cost prohibitive.

They’ll also have issues if their favourite lens on FF was the 85mm 1.8, because there isn’t really a lens that’ll do that job on crop I don’t think.
 
I like the FF equiv of 35/50mm so on APS-C that'd be 24/35mm or there abouts. If you like the same and if you can find a nice used f1.4 in that range that should do nicely. Alternatively if one of your main aims is reduced depth and you can live with alter the framing and perspective, move closer to the subject.

Just a thought... if you can live with manual focus you could look at getting a film era f1.4 or even one of the modern Chinese made manual focus lenses, hopefully in Canon mount or something you can easily adapt. I have three cheap Chinese primes and I do like using them and I'm happy with the results.

Have a look here, there's actually a 33mm f1.4 with AF in Canon mount.

www.pergear.com

Search: 33 results found for "NOT tag:__gift AND f1.4*"

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Phil V said:
They’ll also have issues if their favourite lens on FF was the 85mm 1.8, because there isn’t really a lens that’ll do that job on crop I don’t think.
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Got it in one!

I am due to retire soon, so I will add this task to my ever growing list.
 
Brentor said:
Got it in one!

I am due to retire soon, so I will add this task to my ever growing list.
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Ouch.
You might(?) be happy with a 50mm, which comes out to 80mm on canon crop, frankly I never was. But the 50 I’d recommend is the Sigma Art 1.4 which will get you roughly 80mm f2.

Realistically in your shoes I’d want a 54-56mm.
 
Phil V said:
Which then puts you further away from the subject which also has the function of changing the perspective.

So to answer the OP succinctly; the effective difference in Aperture is approximately 1 stop, which isn’t a great deal in the grand scheme of things.

The 85mm 1.8 on crop would have slightly more DoF than a 135 f2, but not quite as much as a 135 2.8.

In other words, from a purist perspective an 85 1.4 is akin to the 135 f2, but it’s not such a big deal.

The OP’s problems would really start if they had been used to f1.4 lenses, as going wider would be cost prohibitive.

They’ll also have issues if their favourite lens on FF was the 85mm 1.8, because there isn’t really a lens that’ll do that job on crop I don’t think.
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Effectively, using lens FL which is appropriate to the format size, DOF using APS-C is like shooting with FF lens set to 0.6EV smaller aperture
 
Phil V said:
Ouch.
You might(?) be happy with a 50mm, which comes out to 80mm on canon crop, frankly I never was. But the 50 I’d recommend is the Sigma Art 1.4 which will get you roughly 80mm f2.

Realistically in your shoes I’d want a 54-56mm.
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@Phil - do you mean you were never happy with the Canon 1.4 50mm?

I've been toying with the idea of one is all.
 
Sigma make a 17-35 1.8 art, which is a cracking lens for a crop but I dont know if it's available in the R fitting, although I suspect it can work with an adaptor. Getting closer to the subject helps to make the background look more out of focus.
 
Kell said:
@Phil - do you mean you were never happy with the Canon 1.4 50mm?

I've been toying with the idea of one is all.
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I had one back in my Canon days, and produced some of my favourite images with it. I did find it a bit fragile though, I seem to recall it had to have a couple of services in the 8 years I had it, when none of my other Canon lenses needed a service.
 
Kell said:
@Phil - do you mean you were never happy with the Canon 1.4 50mm?

I've been toying with the idea of one is all.
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I was never happy with the FL on crop, not quite long enough for portraits, too long for general shooting.

But I never had the Canon 1.4, I’m not a fan, it’s not a proper USM motor, it’s not sharp till f2.8.
The STM is better in every way (except it’s only 1.8 wide open). And if you really want 1.4 buy the Sigma.
 
Ah I see.

Thanks for the clarification.

I already have two 50mm (including the STM) and no longer have a crop body. Perfectly happy with it, but was curious about the 1.4.

Like you, I found 50mm on a crop body too long for general shooting.
 
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Kell said:
Ah I see.

Thanks for the clarification.

I already have two 50mm (including the STM) and no longer have a crop body. Perfectly happy with it, but was curious about the 1.4.

Like you, I found 50mm on a crop body too long for general shooting.
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I do love the rf50mm and the rf85mm

But my favourite lenses remain the 35mm Sigma and the Canon 135L
 
I think I will use the R7 for bird photography/sports and FF DSLRs for landscapes/portraits etc.
 
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